1. Field of the Invention
The present invention relates to a fiber planted steel sheet comprising a surface treated steel sheet or the like as a substrate, a fiber planting layer which is directly formed on the substrate without a primer made from a synthetic resin containing an anticorrosive pigment formed on the substrate and an electrostatically short fiber planted layer formed on the planting layer and to a production process therefor.
2. Description of the Prior Art
As a prior art to the present invention, there is known a fiber planted steel sheet to be formed which is produced by degreasing the surface of a steel sheet, subjecting it to a chemical conversion treatment with chromic acid to improve adhesion between the steel sheet and a polyester synthetic resin, forming a polyester synthetic resin layer containing an anticorrosive pigment on this surface treated steel sheet, forming on part or all of the surface of the resin layer a reactive acrylic adhesive layer having flexibility which is not broken, cracked or separated at the time of drawing or bending and planting synthetic resin piles on this adhesive layer electrostatically (for example, Japanese Patent Publication No. 27864/1987).
There are known a fiber planted steel material produced by subjecting the surface of an H type steel, steel tube, sheet pile or steel sheet used as a construction steel material to a rust removal treatment with a shot blast, grinder, belt sander or the like, coating it with an acrylic urethane-based adhesive and planting non-metal fibers while it is uncured and a production process therefor (for example, Japanese Patent Disclosure No. 138813/1993).
It is known that a chemical conversion coating film is formed by treating both sides of aluminum or an alloy thereof with chromic acid or chromium phosphate, the film is coated with an acrylonitrile-butadiene copolymer rubber emulsion adhesive and fibers such as nylon pile are planted on this film (Japanese Patent Disclosure No. 34778/1972).
As a prior art related to an electrostatic planting adhesive for a weather strip member used in lower and upper opening/closing portions of car window glass, there is known an adhesive which comprises 100 parts by weight of an ethylene-vinyl acetate copolymer, 1 to 30 parts by weight of a non-yellowing urethane prepolymer (this polymer is a non-yellowing polyisocyanate resin used as a curing agent for an ethylene-vinyl acetate copolymer), 0.1 to 5 parts by weight of a glycidyl silane coupling agent and 0.01 to 5 parts by weight of a wetting agent (Japanese Patent Disclosure No. 145635/1994).
The present applicant proposes an electrostatically fiber planted steel sheet produced by forming a fiber planting layer of a fiber bonding aqueous coating composition comprising an aqueous epoxy modified polyurethane resin, aqueous acidic black dye, antifoaming agent and pH modifier formed on the surface of a surface treated steel sheet and an electrostatically fiber planted layer of organic short fibers on the planting layer (Japanese Patent Disclosure No. 258472/1998).
The above proposal of the present applicant has such an economical problem that an expensive polyurethane resin must be used though an extra step of forming a primer such as a polyester synthetic resin containing an anticorrosive pigment or the like can be eliminated. Since a disperse solvent other than water is separated at the time of drying the fiber bonding aqueous coating composition when a polyurethane resin is used in the fiber bonding aqueous coating composition, means of collecting the disperse solvent is required, resulting in a bulky apparatus.
The present invention provides an electrostatically fiber planted steel sheet produced by using a surface treated steel sheet such as a commercially available galvanized steel sheet (including products treated with a chromate or coated with an organic or inorganic composite film containing no chromium) as a substrate, directly forming a fiber planting layer of an aqueous adhesive composition for planting fibers which is essentially composed of a specific aqueous emulsion resin on the surface of the substrate such as a steel sheet without a primer of a polyester synthetic resin containing an anticorrosive pigment in the prior art on the surface of the substrate, and electrostatically planting short fibers on this planting layer as well as a process for producing the same at a low cost.